It hurts to say this, but what Taare Zameen Par needed was a good director to make it a true masterpiece.
In story-telling, the ends do not justify the means. And when your story lasts 2½ hours, the means are the ends. Taare Zameen Par is a noble effort, messed up in narration. It's like being on a poorly-maintained amusement park roller coaster that suddenly slows down just when the ride is beginning to get exciting, reaches the first sharp curve slower and later than it should, plods along for a while from there, and then takes a short cut to make it to the end in time....